Improvement in the machine for weighing heavy bodies



E. & T. FAIRBANKS.

WeighingHeavy Bodies.

Patented Feb. 10, 1837.

. na'erzazv I ww dim/00 PETERS PhowLithognphu. Wanhinlmn. D C.

UNITED STATES PATENT OFFICE.

ERASTUS FAIRBANKS AND THADDEUS FAIRBANKS, or sr. JOI-INSBURY,

l VERMONT.

IMPROVEMENT IN THE MACHINE FOR WEIGHING HEAVY BODIES For which Letters Patent were granted, dated June 13, 18231, and subsequently canceled on account of a defective specification, and new Letters Patent granted, dated March (5, 1834, which new Letters Patent are hereby canceled on account of a defective specification. l

Specification forming part of Letters Patent No. 1 l 8, dated February 10, L il7.

T 0 all 207L071} it may concern:

' Be 1t known that we, ERASTUS FAIRBANKS and TI-IADDEUS FAIRBANKS, both of St. J ohnsbury, in the county of Caledonia and State of" Vermont, have made an Improvement in the Machine for \Veighing Heavy Bodies, usually called the Platform-Scale, and we do hereby declare that the following is a full and exact description of the same.

\Ve make a frame by taking two pieces of timber for bed-sills, which may be ten inches square and about sixteen feet 1on These are placed parallel to each other about seven feet apart. Across these and nearly at their ends we bolt two timbers, which may be eight by fourteen inches and twelve feet long. These constitute the frame which is to sustain the platform and its appurtenances.

In the accompanying drawings, Figure 1, the two bed-sills are marked 1 l and the two end pieces 1 l. The two pieces marked 2 2 we denominate rockers. These may be eight inches square and nine feet long. They are placed immediately within, having their tops flush with the end timbers, 1 1. To the rockers are attached the hinges and also the levers, to be presently described.

Fig. 2 represents in section one of the bedsills and end timber, the platform, and a hinge, one corner of the apparatus being supposed to be cut through vertically and longitudinally, the numbers, when they are the same, corresponding with similar parts in the other figure.

There are four hinges, one placed at each corner of the machine, each hinge having upon it two knife-edges, one of which rests upon a fulcrum, and the other sustains the platform by hearing against an iron plate upon the under side of the platform. In the drawings the hinge is shown in Fig. 4. The hinges are firmly bolted to the underside of the rockers in such a position that one of its knifeedges projects so far as to receive the plate 5, by which it sustains the platform. The other knife-edge rests on the top of the fulcrum 3, which stands upon the bed-sills l 1.

The rockers are kept in their proper position and act upon the scale-beam by means of two horizontal levers, one proceeding from each rocker, as seen at 7 and 8, Fig. 1. The longer lever, 7, terminates at the side of the platform nearly against the opposite rocker, while the shorter lever terminates at a point equidistant from the axis of each, where it is suspended to the longer lever by a chain, rod, or stirrup.

From the end of the longest lever a rod, 9, extends perpendicularly to a steelyard or common balance, 10, suspended from a fixture for the purpose of ascertaining the weight of any article.

Theadvantages of using but onelever in connection with each pair of hinges are that,

whether it consists of one or more constituent parts, if-each lever be connected. with its rocker or otherwise with its hinges, so as to compose but one moving power, and the two levers be connected at a point equidistant from their axes or center of motion, the arrangement constitutes the most simple combination, and of course avoids much of the friction attending a more numerous combination of levers. Again,- the knife-edge bearings being all on parallel lines, the friction and cramping which would result from an oblique position of the knifeedges is avoided.

The platform upon which the wagon, cart, or other article to be weighed is placed is formed by taking two pieces of timber, which are of suchlength as to passfreely between the two rockers. These are placed parallel to each other directly over the bed-sills, and across them are spiked stout plank nine feet long, so as to form a platform, say, nine by twelve feet. Upon the under side of these longitudinal ti mbers are fastened the plates 5, resting on the inner knife'edge of the hinge, as above described.

The operation of this machine will now be easily understood.

Suppose the two knife edges or bearings upon each hinge to be six inches apart, while the length of the lever from its axis or center of motion to the point where it is suspended by the rod of the steelyard or balance (measuring in a line perpendicular to the parallel lines of the knife-edges) is sixty inches, the

weight of the platform and the articles placed upon it will be ten times the amountindicated by the steelyard or balance; but if the steelyard or balance be attached to the point of the lever one hundred and twenty inches from its axis, the weight will be twenty times the amount indicated by the balance, and so of any proportional difference between these two lengths. The article to be weighed may be placed upon any part of the platform, inasmuch as it is placed upon a similar hinge at each corner, each of which bears the same relation to, and of course exerts the same influence upon, the steelyard rod.

The apparatus above described may be variously modified so as to produce a similar effeetas, for eXample,the rockers may be placed directly under the platform, either in the posi tion hereinbefore set forth or longitudinally within the frame, or the hinges may be bolted to the upper side of the rockers and the projecting knife edges or bearings hanging upon the fulcra, the platform resting upon the other bearings. Again, the knife-edges of the hinges connected with one lever may be farther apart than those of the hinges connected with the other lever, in which case the connecting point of the two levers must obviously be in the center of their relative power.

\Vhat we elai m, and for which we ask a patcut, is

The knife-edge hinges constructed in the manner hereiubefore set forth, and the pieces denominated rockers, asshownin the drawlugs.

In testimony that the foregoing is a true specification of our said improvements, as hereinbefore described, We have hereunto set our hands this 21st day of January, A. D. 1837.

EB ASTUS FAIRBANKS. THADDEUS FAIRBANKS.

Witnesses:

LUTHER JEWETT, HIRAM KNAPP. 

